Blood Pool Segmentation Results in Superior Virtual Cardiac Models than Myocardial Segmentation for 3D Printing

Abstract

The method of cardiac magnetic resonance (CMR) three-dimensional (3D) image acquisition and post-processing which should be used to create optimal virtual models for 3D printing has not been studied systematically. Patients (n = 19) who had undergone CMR including both 3D balanced steady-state free precession (bSSFP) imaging and contrast-enhanced magnetic resonance angiography (MRA) were retrospectively identified. Post-processing for the creation of virtual 3D models involved using both myocardial (MS) and blood pool (BP) segmentation, resulting in four groups: Group 1-bSSFP/MS, Group 2-bSSFP/BP, Group 3-MRA/MS and Group 4-MRA/BP. The models created were assessed by two raters for overall quality (1-poor; 2-good; 3-excellent) and ability to identify predefined vessels (1-5: superior vena cava, inferior vena cava, main pulmonary artery, ascending aorta and at least one pulmonary vein). A total of 76 virtual models were created from 19 patient CMR datasets. The mean overall quality scores for Raters 1/2 were 1.63 ± 0.50/1.26 ± 0.45 for Group 1, 2.12 ± 0.50/2.26 ± 0.73 for Group 2, 1.74 ± 0.56/1.53 ± 0.61 for Group 3 and 2.26 ± 0.65/2.68 ± 0.48 for Group 4. The numbers of identified vessels for Raters 1/2 were 4.11 ± 1.32/4.05 ± 1.31 for Group 1, 4.90 ± 0.46/4.95 ± 0.23 for Group 2, 4.32 ± 1.00/4.47 ± 0.84 for Group 3 and 4.74 ± 0.56/4.63 ± 0.49 for Group 4. Models created using BP segmentation (Groups 2 and 4) received significantly higher ratings than those created using MS for both overall quality and number of vessels visualized (p < 0.05), regardless of the acquisition technique. There were no significant differences between Groups 1 and 3. The ratings for Raters 1 and 2 had good correlation for overall quality (ICC = 0.63) and excellent correlation for the total number of vessels visualized (ICC = 0.77). The intra-rater reliability was good for Rater A (ICC = 0.65). Three models were successfully printed on desktop 3D printers with good quality and accurate representation of the virtual 3D models. We recommend using BP segmentation with either MRA or bSSFP source datasets to create virtual 3D models for 3D printing. Desktop 3D printers can offer good quality printed models with accurate representation of anatomic detail.

Three‐dimensional printing in congenital heart disease: A systematic review

“…Of the 28 articles, 17 of them (61%) were case reports and case series, based on number of cases ranging from 1 to 12 cases with different CHD and cardiovascular diseases. Ten of them (36%) were cross‐sectional studies, mainly surveying the healthcare professionals, parents, parents of patients and medical students; and 3 of which were randomised controlled trials.…”

“…Overall, analysis of these studies shows that 3D printed models serve as a useful and effective tool to improve understanding of complex cardiac structures in relation to the CHD and enhance the confidence level of cardiologists in planning cardiac interventions. With graspable models in hand, the 3D printed models have shown great promise in enhancing the perception of distances, dimensions and spatial information of the complex cardiac morphology, and therefore facilitate the decision‐making for treatment plans . The 3D printed models were reported to help the surgeons in deciding best surgical treatment when optimum surgical approach could not be finalised based on traditional diagnostic tools .…”

“…In addition, the intra‐operative time was also shortened with an improved surgical outcome . However, few studies pointed out that the 3D printed heart models only complement the current diagnostic tools, and should not be stand‐alone tools for preoperative planning …”

Three-dimensional printing in cardiology: Current applications and future challenges

“…Without image postprocessing, the quality of a 3D-printed model is poor [31]. A new method called blood pool segmentation has been recently proposed to more accurately extract the region of interest for 3D printing [32]. Integration of multiple imaging modalities may be a good solution in acquiring high-quality medical images.…”

Virtual 3D Modeling of Airways in Congenital Heart Defects

“…The segmentation of cardiovascular and airway structures was obtained by using Mimics 18 ® and following the segmentation process using the blood pool technique as described by Farooqi et al (12). Once each individual structure was identified and associated with a corresponding mask, the 3D volumetric rendering was obtained.…”